Method for manufacturing a plate-type heat pipe

ABSTRACT

A method for manufacturing a plate-type heat pipe including providing a mold including a first cavity and a plurality of second cavities located above and communicating with the first cavity and depositing cores into the first cavity. First and second metal powder are injected into the mold by using a double-mode injection molder. The first metal powder securely adheres to the cores, and the second metal powder fills up the first and second cavities except the first metal powder located, thereby forming a green piece. The cores are removed from the green piece to define chambers in the green piece. The green piece is heated to obtain a sintered product with an outer wall, fins extending from the outer wall and a wick structure adhering inner surfaces of the outer wall.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure relates to a method for manufacturing a plate-type heat pipe, and more particularly to a method for manufacturing a plate-type heat pipe which utilizes technologies of metal injection molding and powder sintering.

2. Description of related art

Generally, plate-type heat pipes efficiently dissipate heat from heat-generating components such as a central processing unit (CPU) of a computer. A conventional plate-type heat pipe comprises a case formed by stamping a metal sheet to have an engaging plate and a base plate defining a trough. A plurality of fins is welded on a top surface of the engaging plate. The case contains working fluid therein. A wick structure is laid on an inner wall of the base plate and an inner wall of the engaging plate. The base plate and the engaging plate are assembled together by welding. It is difficult to precisely weld the base plate and the engaging plate together, whereby the base plate and the engaging plate may not be hermetically connected together, or the welding strength is not sufficient to meet the required value. In addition, the welded connection between the engaging plate and the fins has a thermal resistance hindering a smooth and efficient heat transfer from the engaging plate to the fins.

It is therefore desirable to provide a method for manufacturing a plate-type heat pipe overcoming the shortcomings of the conventional art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a cross-sectional view showing a mold for forming a plate-type heat pipe in accordance with a first embodiment of the disclosure.

FIG. 2 is a cross-sectional view of a green piece for forming the plate-type heat pipe in accordance with the first embodiment of the disclosure, wherein the green piece is formed by and removed from the mold of FIG. 1.

FIG. 3 is a cross-sectional view of a plate-type heat pipe in accordance with the first embodiment of the disclosure.

FIG. 4 is a cross-sectional view of a plate-type heat pipe in accordance with a second embodiment of the disclosure.

FIG. 5 is a perspective view showing fins of a plate-type heat pipe in accordance with a third embodiment of the disclosure.

FIG. 6 is a perspective view showing fins of a plate-type heat pipe in accordance with a fourth embodiment of the disclosure.

FIG. 7 is a perspective view showing fins of a plate-type heat pipe in accordance with a fifth embodiment of the disclosure.

FIG. 8 is a perspective view showing fins of a plate-type heat pipe in accordance with a sixth embodiment of the disclosure.

FIG. 9 is a perspective view showing fins of a plate-type heat pipe in accordance with a seventh embodiment of the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-3, a method for manufacturing a plate-type heat pipe 10 in accordance with a first embodiment of the disclosure will be explained in the following. Firstly, a mold 90 is provided. The mold 90 consists of an upper half (not labeled) and a lower half (not labeled), wherein when the mold 90 is closed as shown in FIG. 1, the mold 90 defines therein a large, cuboidal first cavity 91 and a number of small, cuboidal second cavities 93 located at a top of the first cavity 91 and communicating with the first cavity 91. The first and second cavities 91, 93 cooperatively define a cavity which has structure and size corresponding to those of the plate-type heat pipe 10.

Secondly, a plurality of spaced cores 30 of a material releasable by thermal cracking reaction or chemical reaction is deposited into the first cavity 91 of the mold 90. Each core 30 has a cuboidal configuration and a number of pores therein. A web (not shown) extends through the cores 30 to connect the cores 30 together as a single unit.

Thirdly, a first metal powder with particle diameter from 5 μm to 90 μm and a second metal powder with particle diameter from 50 μm to 150 μm are respectively injected into the first and second cavities 91, 93 of the mold 90 using two injection systems with opposite injection directions. As a result, the second metal powder covers the cores 30 and fills the pores of the cores 30, and the first metal powder fills the first and second cavities 91, 93 of the mold 90 except the second metal powder located, thereby forming a green piece. The injection systems is in a double-mode injection molder (not shown).

Fourthly, the cores 30 are removed from the green piece by thermal cracking reaction or chemical reaction, thereby defining a number of hollow, cuboidal chambers 15 in the green piece.

Finally, the green piece with the chambers 15 defined therein undergoes a series of processes to become the plate-type heat pipe 10. The green piece is disposed in a sintering oven and sintered at a high temperature, whereby the first and second metal powders are bound together to obtain a sintered workpiece. The chambers 15 are vacuumed and filled with a working fluid (not shown) such as water, alcohol, methanol, or the like, via a port in the workpiece. Finally, the port in the workpiece is hermetically sealed. As a result, the desired plate-type heat pipe 10 is obtained and includes a tight, hermetic outer wall 11, a plurality of cuboidal fins 13 extending upwardly from a top surface of a side of the outer wall 11, and a wick structure 14 thermally contacting with inner surfaces of the outer wall 11. The wick structure 14 includes a number of supporting poles 17 between top and bottom ends of the outer wall 11 to enhance the strength of the plate-type heat pipe 10. In this state, the outer wall 11 and the fins 13 are made of the first metal powder, and the wick structure 14 including the supporting poles 17 is made of the second metal powder.

Each of the cores 30 is comprised of a polymer or waxy material. After the cores 30 are removed, the green piece defines the chambers 15 to receive the working fluid (not shown) therein. The supporting poles 17 and the wick structure 14 are porous and communicate with each other, therefore the working fluid can quickly flow from a top end of the wick structure 14 to a bottom end of the wick structure 14 along lengthways directions of the supporting poles 17. The fins 13 integrate with the outer wall 11 of the plate-type heat pipe 10. Thus, heat resistance between the fins 13 and the outer wall 11 is significantly reduced relative to the conventional plate-type heat pipe. The heat dissipation efficiency of the plate-type heat pipe 10 is accordingly improved.

Referring to FIG. 4, a plate-type heat pipe 20 is manufactured using the method previously described. The plate-type heat pipe 20 is similar to the plate-type heat pipe 10. Difference between the plate-type heat pipes 10, 20 is that each of the chambers 25 of the plate-type heat pipe 20 has a configuration different from that of each of the chambers 15 of the plate-type heat pipe 10. Each of the chambers 25 of the plate-type heat pipe 20 has a trapezoid cross section with a larger top side and a smaller bottom side. Meanwhile, each chamber 15 of the plate-type heat pipe 10 has a rectangular cross section. A configuration of each of the chambers 25 is identical to that of each of the cores for forming a corresponding chamber 25. Thus, the cores in this embodiment each have a configuration of a trapezoid block.

Referring to FIG. 5, a top portion of the outer wall 31 and fins 33 of a plate-type heat pipe 30 are shown. The plate-type heat pipe 30 is manufactured using the method described in the first embodiment. Difference between the plate-type heat pipes 10, 30 is that a configuration of each of the fins 33 of the plate-type heat pipe 30 is different from that of each of the fins 13 of the plate-type heat pipe 10. In this embodiment, each of the fins 33 has a configuration of a cone. Bottom ends of the fins 33 each having the largest area for a corresponding fin 33 can absorb heat of the plate-type heat pipe 30 quickly.

Referring to FIG. 6, fins 43 of a plate-type heat pipe 40 are shown. The plate-type heat pipe 40 is manufactured using the method described in the first embodiment. Difference between the plate-type heat pipes 30, 40 is that the configuration of each of the fins 33 of the plate-type heat pipe 30 is different from that of each of the fins 43 of the plate-type heat pipe 40. In this embodiment, each of the fins 43 has a configuration of a round rod.

Referring to FIG. 7, fins 53 of a plate-type heat pipe 50 are shown. The plate-type heat pipe 50 is manufactured using the method described in the first embodiment. Difference between the plate-type heat pipes 30, 50 is that the configuration of each of the fins 33 of the plate-type heat pipe 30 is different from that of each of the fins 53 of the plate-type heat pipe 50. In this embodiment, each of the fins 53 has a configuration of a rectangular rod. The fins 53 are arranged in a matrix on a top portion of the outer wall.

Referring to FIG. 8, fins 63 of a plate-type heat pipe 60 are shown. The plate-type heat pipe 60 is manufactured using the method described in the first embodiment. Difference between the plate-type heat pipes 50, 60 is that the configuration of each of the fins 53 of the plate-type heat pipe 50 is different from that of each of the fins 63 of the plate-type heat pipe 60. In this embodiment, each of the fins 63 has a configuration of a rhombus rod. The fins 63 are arranged into a matrix with a plurality of rows and columns. Two neighboring fins 63 of a same column is spaced a distance smaller than that between two neighboring fins 63 of a same row.

Referring to FIG. 9, fins 73 of a plate-type heat pipe 70 are shown. The plate-type heat pipe 70 is manufactured using the method described in the first embodiment. Difference between the plate-type heat pipes 30, 70 is that the configuration of each of the fins 33 of the plate-type heat pipe 30 is different from that of each of the fins 73 of the plate-type heat pipe 70. In this embodiment, each of the fins 73 has a configuration of a circular frustum. Bottom end is larger than top end of each of the fins 73.

In this disclosure, configuration and size of each of the fins are decided by those of each of the second cavities 93 of the mold 90. As long as the configuration and size of the second cavity 93 of the mold 90 are changed, various plate-type heat pipes with various fins can be obtained. Similarly, structure and size of the outer wall 11, the wick structure 14 and the supporting poles 17 can be varied by changing structure and size of the first cavity 91 and the cores 30.

It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention. 

1. A method for manufacturing a plate-type heat pipe comprising: providing a mold comprising a first cavity and a plurality of second cavities located at a top of the first cavity and communicating with the first cavity; depositing a plurality of cores into the first cavity of the mold; filling a first metal powder and a second metal powder respectively into the first and second cavities of the mold in such a manner that the first metal powder covers the cores, and the second metal powder fills the first and second cavities except the first metal powder located, thereby forming a green piece; removing the cores from the green piece to define a plurality of chambers therein; sintering the green piece with the chambers defined therein to obtain a sintered workpiece, wherein the sintered workpiece has an outer wall and a plurality of fins extending upwardly from a top side of the outer wall; vacuuming the chambers; injecting a working fluid into the chambers via a port in the sintered workpiece; and sealing the port of the sintered workpiece.
 2. The method for manufacturing a plate-type heat pipe as in claim 1, the first and second metal powder are filled in the mold by using a double-mode injection molder.
 3. The method for manufacturing a plate-type heat pipe as in claim 1, wherein each of the second cavities of the mold has one of following configurations: a cuboidal configuration, a cone-shaped configuration, a round rod-shaped configuration, a rectangular rod-shaped configuration, a rhombus rod-shaped configuration and a circular frustum-shaped configuration, and the second cavities are spaced from each other.
 4. The method for manufacturing a plate-type heat pipe as in claim 3, wherein each of the second cavities has a configuration of a rhombus rod-shaped configuration, the second cavities are arranged in a matrix having a plurality of rows and columns, a space between two neighboring second cavities of a same column is smaller than that between two neighboring second cavities of a same row.
 5. The method for manufacturing a plate-type heat pipe as in claim 1, wherein the second cavities of the mold are arranged in to a matrix.
 6. The method for manufacturing a plate-type heat pipe as in claim 1, wherein the first cavity of the mold is cuboidal.
 7. The method for manufacturing a plate-type heat pipe as in claim 6, wherein the cores disposed in the first cavity of the mold are spaced from each other.
 8. The method for manufacturing a plate-type heat pipe as in claim 1, wherein a particle size of the first metal powder is larger than that of the second metal powder.
 9. The method for manufacturing a plate-type heat pipe as in claim 1, wherein each of the cores is made of one of a polymer material and a waxy material.
 10. The method for manufacturing a plate-type heat pipe as in claim 1, wherein each of the cores is removed from the green piece by one of thermal cracking and chemical reaction.
 11. A plate-type heat pipe comprising: a hermetic outer wall; a plurality of spaced fins extending upwardly from a top surface of the outer wall, wherein the outer wall and the fins are of a same metal and integrally formed as a single piece; a wick structure contacting with inner surfaces of the outer wall; at least a chamber defined in the wick structure; and a working liquid received in the at least a chamber.
 12. The plate-type heat pipe as in claim 11, wherein a plurality of spaced supporting poles is formed by the wick structure and located between top and bottom ends of the outer wall.
 13. The plate-type heat pipe as in claim 12, wherein the supporting poles and the wick structure are porous.
 14. The plate-type heat pipe as in claim 11, wherein each of the fins has one of following configurations: a cuboidal configuration, a cone-shaped configuration, a round rod-shaped configuration, a rectangular rod-shaped configuration, a rhombus rod-shaped configuration and a circular frustum-shaped configuration, and the fins are spaced from each other.
 15. The plate-type heat pipe as in claim 14, wherein each of the fins has a configuration of a rhombus rod-shaped configuration, the fins are arranged in a matrix having a plurality of rows and columns, a space between two neighboring fins of a same column is smaller than that between two neighboring fins of a same row. 